1. Field of the Invention
This invention relates generally to the field of perpendicular magnetic recording (or write) heads and more particularly, to a main pole within the write head being made with a polyimide mask with improved removal thereof to form the main pole and planarized main pole onto which trailing shield is formed to increase head performance.
2. Description of the Prior Art
As the recording density of magnetic hard drives (or disc drives) increases, a physical limitation is experienced using longitudinal recording systems partly due to thermal relaxation known as super-paramagnetism. That is, the density requirements for meeting today's storage needs are simply not attainable with longitudinal recording systems. To provide further insight into this problem, it is anticipated that longitudinal recording systems will lose popularity as storage capacities in excess of about 150 Gigabytes-per-square-inches become a requirement. These and other factors have lead to the development and expected launch of perpendicular recording heads or write heads. Perpendicular recording is promising in pushing the recording density beyond the limit of longitudinal recording.
Accordingly, perpendicular recording potentially supports much higher linear density than longitudinal recording due to lower demagnetizing fields in recorded bits.
A magnetic recording head for perpendicular writing generally includes two portions, a writer portion for writing or programming magnetically-encoded information on a magnetic media or disc and a reader portion for reading or retrieving the stored information from the media.
The writer of the magnetic recording head for perpendicular recording typically includes a main pole and a return pole which are magnetically separated from each other at an air bearing surface (ABS) of the writer by a nonmagnetic gap layer, and which are magnetically connected to each other at a back gap closure (yoke). This structure is a single-pole write head because while a main pole and return pole are referred thereto, the return pole is not physically a pole, rather, it serves to close the loop with the main pole and the soft under layer of the media to form a magnetic flux circuit.
Positioned at least partially between the main and return poles are one or more layers of conductive coils encapsulated by insulation layers. The ABS is the surface of the magnetic head immediately adjacent to the perpendicular medium.
To write data to the magnetic medium, an electrical current is caused to flow through the conductive coil, thereby inducing a magnetic field across the gap between the main and return poles. By reversing the polarity of the current through the coil, the polarity of the data written to the magnetic media is also reversed.
The main and return poles are generally made of a soft magnetic material. The main pole generates magnetic field in the media during recording when the write current is applied to the coil. A magnetic moment of the main pole should be oriented along an easy axis parallel to the ABS when the main pole is in a quiescent state, namely without a write current field from the write coil.
With the advent of perpendicular recording heads, density has been greatly increased, as discussed hereinabove, which has lead to a greater need for accurate recording of data onto the desired track. That is, writing to adjacent tracks is highly undesirable because it causes corruption of data on adjacent tracks.
Perpendicular write heads generally have a trailing shield, side shields, a top pole and a bottom return pole. The main pole is generally shaped in a manner causing a tip or an extension thereof that is narrower than the remaining portion thereof to form a top pole. The side shields act to shield the top pole so as to reduce adverse affects on adjacent tracks during the writing of magnetic transitions (data) at a location on a given track.
In the recording head, namely the slider, the main and return poles are separated by the gap layer, causing writing of data onto tracks. The main pole is generally beveled in shape in an effort to reduce adjacent track writing.
There are problems associated with the formation of the main pole and particularly the top pole in perpendicular heads. Two such problems are now presented. First, to form the main pole, an N-methyl pyrrolidone (NMP) soluble polyimide is used but then removed to form the pole. The polyimide layer is milled prior to its removal and the milling process adds difficulty to the removal of the polyimide layer, as fences or sidewalls remain behind and in the event such fences fall, voids are caused, which adversely affect head performance. Second, the main pole, which includes a top pole, as previously discussed, need be planarized or leveled, at its surface, so as to properly form a trailing shield thereupon.
Thus, in light of the foregoing, there is a need for a perpendicular recording head having a main pole (or write pole) developed in such a way so as to planarize the same for trailing shield formation thereupon and to improve polyimide layer removal during formation of the main pole to improve performance of the head.